In recent years, an on-vehicle disk reproducing apparatus for playing back an optical disk such as a CD or a DVD employs a slot-in system, which does not have a tray for loading and unloading the disk and in which a disk is directly inserted in a slit-like opening so as to effectively use the limited space inside the vehicle. This system automatically performs a loading operation for carrying a disk, which is inserted in a predetermined position of the opening, to a reproducing position automatically and for placing the disk on a turntable, and an ejecting operation for removing the disk on the turntable therefrom after playback and for carrying the disk to the position where the disk can be grasped and removed through the opening. In this disk reproducing apparatus, there is a state where the disk is considerably exposed from the slit opening at the loading time and also at the ejecting time, and thus there is a possibility that a user presses in the disk or pulls it out by force. Therefore, a detecting means for watching not only a loading start position and an ejection end position but also the position of the disk within the disk reproducing apparatus is required.
In on-vehicle disk reproducing apparatuses, there is a technology enabling the position of a disk to be surely detected during the period of time from loading start to ejection end, using a plurality of photosensors (see FIG. 11 shown as a conventional example in Patent Document 3, for instance). However in practice, since a photosensors is expensive, a disk position detecting means using two photosensors, as shown in FIG. 5 herein, is employed. In FIG. 5, reference numerals 4a, 4b, and 4c denote the positions of a disk 4. A chassis 1 has attached on the center thereof a turntable 3, a spindle motor (not shown) for rotating and driving the turntable, and an optical pickup 5 for reading signals. The chassis has provided on the side of opening 11, through which the disk is inserted or removed, a photosensor A, a sending roller 2, and a photosensor B in the order toward the center of the chasses. The photosensors A and B each are a transmission type or a reflection type photosensors combining an LED with a photosensor, as is commonly known.
When the disk 4 is inserted through the opening 11 and comes to the loading start position 4a, the photosensor A turns on because light thereto is intercepted by the disk 4, and then the sending roller 2 rotates responding to the detection output therefrom. When the disk 4 is further inserted to be loaded onto the sending roller 2, the disk is transferred inwardly by the roller 2. When the disk 4 reached an ejection end position 4b on a transfer process, the light to other photosensor B is also intercepted and therefore photosensor B turns on. When the disk 4 is further transferred by the roller 2 to the reproducing position 4c, the edge of the disk 4 abuts against a roller stop switch (not shown) to turn on the switch and thereby the sending roller 2 stops, though those operations are generally known. The disk 4 is released from the sending roller 2 at the reproducing position 4c to be placed on the turntable 3, and then goes into a reproducible state. Then, when an ejecting switch (not shown) is pressed by a user, the disk 4 goes into the ejecting state where the disk is removed from the turntable 3 and is carried toward the opening 11 by the sending roller 2 rotating in a direction opposite to that in the loading. When the disk 4 comes to the ejection end position 4b to be moved off from the photosensor B, the photosensor B is switched from the “on” to the “off”, and the sending roller 2 stops responding to the detection output. Under such a condition, the center hole of the disk 4 is exposed from the opening 11 so that pulling out the disk therefrom with the fingers becomes possible. When the disk 4 is taken out therefrom to be moved off from the position 4a, the photosensor A also turns off. In a series of operations described above, as to the detection operation of the photosensors A and B with respect to the disk 4, the sensor A is in the on-state during the period of time from the loading start to the ejection end and the photosensor B remains in the on-state from loading to ejecting, as shown in FIG. 6, thus accurately indicating the position of the disk 4 within the apparatus.
However, when the system for detecting the disk is built with photosensors as described above, since a photo sensor is expensive and wiring lines for supplying power and detecting signals, a control board, and electronic parts are required; their cost tends to be relatively high. For this reason, as an inexpensive detecting mechanism, the following technology is disclosed: a detecting lever rotating upon abutment of a disk is provided, a microswitch (hereinafter, referred to simply as a “switch”) is operated by the microswitch, to thus detect the position of a disk (see Patent Document 1, Patent Document 2, and Patent Document 3, for instance).
Examples of the structure of the disk position detecting means employing two switches and switching with a disk detecting lever are shown in FIG. 7 to FIG. 9 and will be discussed. A disk detecting lever 6 is attached so as to rotate about a shaft 6d provided on, e.g., the left side on the opening side of a chassis, and is always urged counterclockwise by a spring (not shown) in a state that a disk 4 has not been inserted, such that a detecting pin 6a for detecting the outer edge of the disk is located on the opening side thereof. Further, the disk detecting lever 6 has a switch abutting section 6b on the circumference thereof. The disk reproducing apparatus has disposed at a predetermined position on the chassis thereof, a switch C for defining the loading start position and a switch D for defining the ejection end position, so that the respective actuators of the switches oppose the circumference of the disk detecting lever 6. In this structure, the amount of the rotation of the disk detecting lever 6 is the same at the disk positions 4a and 4d in FIG. 8 and is the same at the disk positions 4b and 4e in FIG. 9.
In FIG. 8, when the disk 4 is inserted and comes to the loading start position 4a, the outer edge of the disk 4 abuts against the detecting pin 6a attached to the disk detecting lever 6 and then a force pushing the detecting pin 6a toward the outer peripheral direction of the chassis is applied. Therefore, the disk detecting lever 6 rotates clockwise, and the switch abutting section 6b provided on the circumference of the lever abuts against the switch C and switches the switch C from “off” to “on.” Upon such a switching process, the switch C detects the insertion of the disk 4 and the sending roller 2 rotates responding to the detection output from the switch. When the disk 4 is further inserted to be loaded onto the sending roller 2, the disk is automatically transferred toward the center of the disk reproducing apparatus by the sending roller 2. As the disk 4 proceeds, the disk detecting lever 6 also rotates clockwise, and when the disk 4 comes to the position 4b as shown in FIG. 9, the switch abutting section 6b abuts against the switch D. When the disk 4 exceeds over the position 4b, the switch D is switched from “off” to “on” by the switch abutting section 6b. When the disk 4 further proceeds, since the detecting pin 6a exceeds the maximum excursion and then returns, the switch abutting section 6b moves off from the switch D at the position 4e shown in FIG. 9 and thereby the switch D turns off. Moreover, as the disk 4 approaches the position 4d, the detecting pin 6a further returns, and when the disk 4 exceeds the position 4d, the switch C turns from “on” to “off” as shown in FIG. 8. Accordingly, the disk 4 reaches the reproducing position 4c when both switches C and D are “off”. At this time, the edge of the disk 4 abuts against a roller stop switch (not shown) to turn on the switch and thereby the sending roller 2 stops. The disk 4 is released from the sending roller 2 at the reproducing position 4c to be placed on the turntable 3, and goes into a reproducible state. Then, when an ejecting switch is pressed by a user, the disk 4 is removed from the turntable 3 and goes into the ejecting operation where the disk is carried toward the opening 11 by the sending roller 2 rotating in a direction opposite to that in the loading. At this time, the disk 4 travels via the positions 4c, 4d, 4e, and 4b opposite those in the loading, and thus the switches C and D go through the switching states as shown in FIG. 10 along the movements of the disk detecting lever 6.    Patent Document 1: JP-A 10-116459 (1998-116459)    Patent Document 2: JP-A 2005-222600    Patent Document 3: JP-A 10-162466 (1998-162466)
When the loading start position and the ejection end position are arranged to be detected by two switches and the disk detecting lever in place of photosensors as discussed above, there are the following problems.
As shown in FIG. 9, the amount of rotation of the disk detecting lever 6 is the same at the disk positions 4e and 4b in the ejecting stage, and thus the switches C and D indicates the same state of detection. In other words, there is the moment in time at which the position (detection state) of the disk on the way of the ejection becomes the same as the position (detection state) of the disk at the ejection end position. For this reason, when the disk is mistakenly pressed in, for example, even though while the disk is being ejected and not yet goes into a state of ejection end, it can be considered that the ejection has been completed. In this case, even if a user operates it again at this time, the disk stays within the apparatus and is not ejected therefrom. Further, when the power is turned off on the way of the ejection process and then the power is turned on again, the same state also occurs, where the apparatus cannot detect the disk position.
In order to solve the problem, the switches C and D should be always held in the on-state during the period of time from the loading start to the ejection end. The switch C for detecting the disk insertion can be always kept in the on-state during the period of time from the loading start to the ejection end as described also in Patent Document 2 and Patent Document 3; however, always holding the switch D in the on-state during the period of time from the loading start to the ejection end cannot be actually carried out since the mechanism is very complicated.
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a disk reproducing apparatus enabling the insertion condition of a disk to be surely detected by a compact and low-cost structure using a single photosensor, a single switch and a disk detecting lever.